Now this is the argument a Lutheran may potentially use against the Catholic teaching of the complete transformation of substance.
Or by any protestant not affirming the Holy Eucharist (as Catholics do).
"If the substance of bread is completely removed, then a man who is allergic to whatever is in the bread used to make the wafers should have no problem with taking Catholic Communion. But, as I know from a Catholic friend of mine, who actually is allergic to the elements found in bread (i. e. the wafer), he must be given a specially made wafer which does not contain whatever he is allergic to, when taking Communion.
It would seem that the substance of bread is not gone. It would seem either:
a) that no change has been made
b) that the change is not a complete change of substance - rather the substance of bread and the substance of Christ co-exist.
A reply that springs to my mind would be that substance is something divided from the chemical properties of the host.
Your takes on this one?